The invention relates to self-propelled irrigation equipment of the kind distributing water through parallel open-ended hoses while moving across a field.
U.S. Pat. No. 4,283,010 teaches a method of irrigating fields along parallel rows of plants by causing water to flow through a plurality of open-ended flexible hoses laid out in parallel alignment between each two planted rows and by pulling the ends of the hoses gradually along these rows at a speed proportional to the quality of water delivered. The method is carried out by an implement comprising a rotating pair of grooved pulleys for each hose which are adapted to drag the hoses from the farthest point to which they are laid, while water is flowing out of their open ends, down to the location of the implement, whereafter the water supply to the hoses is turned off. After a section has been irrigated, the implement and the hoses are transported to another location or field section for a similar course. By means of this method uniform irrigation for all parallel rows and all along every row is made possible, without any waste of water.
Although the devices working according to the above method give excellent results, they are mostly suitable for small and medium-size plantations; in case huge tracts of land have to be irrigated, such as cotton plantations, transporting of the implement and the hoses from section to section requires relatively much manpower and time. Another drawback of this system, especially if very long hoses are used, is the energy required for dragging the hoses along the rows across the soil, the friction being considerable owing to the heavy weight of the water-filled hoses.
With these drawbacks in view, self-propelled watering implements have been developed in the recent past and are used in the irrigation of vast tracts of land. These irrigation machines consist of large vehicles provided with a long boom extending perpendicular to the direction of travel to both sides of the vehicle and carrying a water-distribution pipe provided with equidistant spouts.
These vehicles are usually driven by an internal combustion engine, as their motion requires considerable energy. Their course is along a water main provided with a hose connection every 30 to 50 m, which serves to supply water to the distribution pipe through a flexible hose of sufficient cross section. During travel of the vehicle between adjacent hose connections the flexible hose is dragged across the soil which not only results in considerable expense of energy but also in increased wear of the hose. Owing to the large drag force acting on the vehicle, it became necessary to provide strong diesel engines, strong tires and a generally strong structure which, obviously, results in heavier weight of the implements which, in their latest embodiments, have become veritable mammoths.
The present invention was made with the object of providing self-propelled irrigation equipment of light weight using little energy, by propelling it by means of a hydraulic actuator which should use only a small portion of the pressure energy contained in the distributed water itself. This demand leads automatically to the requirement of reducing the drag of the connecting hose and, consequently, of making the vehicle itself of light weight.
With those objects in view the irrigation equipment is characterised by the following features: (1) the use of a large drum for gathering on it a connecting hose of about 200 m leading to a water connection in the field. (2) the use of hydraulic actuators adapted to propel the implement and to rotate the drum for respective winding or unwinding of the above hose. (3) Means for propelling the vehicle across the field at a velocity proportional to the water quantity distributed at every moment.
One embodiment of the self-propelled irrigation equipment, according to the invention, comprises a vehicle provided with at least two driving wheels on a common shaft, with at least one free caster wheel, and with hydraulic actuator means adapted to rotate said shaft and said driving wheels; a drum positioned on said vehicle mounted on a shaft parallel to said driving wheel shaft and adapted to be rotated by hydraulic actuator means, said shaft having one hollow end portion; a flexible hose stretched out on the ground to be irrigated, having a first end connected to a stationary water supply point and a second end fastened to said drum shaft communicating with said hollow shaft portion, said hose being adapted to be wound upon, or wound off, said drum at the rate of progress of said vehicle in relation to said water supply point; a water distribution pipe connected to said vehicle extending transversely to both sides of said vehicle and improved with a plurality of, preferably equidistant, water outlets; pipe means for communicatingly connecting said hollow portion of said drum shaft with said distribution pipe; and means for controlling the velocity of said vehicle and of said distribution pipe proportional to the water flow passing through said flexible hose to said distribution pipe.
The vehicle is preferably provided with two drive wheels and one swivelling wheel; the water distribution pipe is carried on a girder extending to both sides of the vehicle, either cantilevered or supported by outer carriages, this girder being foldable about vertical pivots in order to shorten it for transport, and being raised above the ground to permit its passage over the head of high plants.
In a preferred embodiment the vehicle is driven by a hydraulic linear actuator which rotates the driving wheel shaft by means of a pawl-and-ratchet mechanism. The drum is driven by the driving wheel shaft through a belt drive having a high slip-capacity, which allows the drum to be rotated at a slower rate or in opposite sense of rotation to that of the driving wheels, while the hose is unwound off the drum.
The vehicle velocity is controlled by means of a watermeter installed in the line connecting the second end of the hose attached to the drum to the distribution pipe, the watermeter being adapted to transmit suitable signals to a regulating valve installed in the water supply line to the hydraulic actuator.
The implement operates to both sides of a stationary water supply point, e.g. an outlet valve on a water main, whereby the distance travelled by the vehicle is twice the length of the hose. Starting with the hose fully extended, the vehicle will be at a distance of, say, 200 m from the water connection. After the valve has been opened, water flows through the flexible hose and through the drum into the distribution pipe from where it is poured, preferably through short hose sections, into ditches between rows of plants, thus every row obtaining the same water quantity. A part of the total flow is directed into the actuator which drives the vehicle in the direction of the water connection, at a speed proportional to the water supplied through the flexible hose. At the same time the belt drive rotates the drum at a speed slightly faster than would be necessary to wind up the hose, but owing to the resistance of this hose, the belt slips and the hose is wound upon the drum in a few concentric layers. The entire hose is wound upon the drum when the vehicle has reached the connection point. The vehicle continues on its way across this point, and now the hose is unwound off the drum, this being done against the direction of the belt drive which is sufficiently slack to slip under the load. The vehicle is stopped after the entire length of hose has been uncoiled and lies on the ground between the vehicle and the water connection point. The hose is disconnected from the water connection and connected to the following water connection point, whereafter the process is repeated along another stretch of planted area.
Another, move advantageous, manner of operating the implement is to have it travelling twice across the course; starting from the water connecting point with the entire hose wound upon the drum, the vehicle moves away from this point stretching the hose on the ground; the vehicle now returns on its tracks and winds the hose on the drum until it reaches the water point and continues its way in the other direction; on the last stretch it returns to the water point and reaches it with the hose again fully wound on the drum. In this state the implement is readily transported to another section, after the hose has been disconnected and is ready for connection to another connection point. This manner of operation is also advantageous from an irrigation point of view, as only half the necessary quantity of water is distributed during each course which is more easily absorbed by the soil. Compared with the existing methods and apparatus, the main advantage of the present implement is that no energy is wasted in dragging hoses over the ground, permitting a smaller actuator to be used and less pressurised water to be consumed. The energy required for moving the vehicle and the distribution pipe over the ground and for winding up the hose is relatively small, and field tests have shown that a pressure head of 3 m is sufficient to propel the vehicle.
Another embodiment of the invention comprises a vehicle provided with one driven swivel wheel and two free wheels mounted on a common axle, wherein the hose drum and the swivel wheel are each driven by a separate hydraulic linear actuator, both actuators being operated by water passing through the flexible hose to the distribution pipe onto the field to be irrigated. Regulation of the respective speed of the drum and the vehicle is effected by the relative resistance of both driving mechanisms, in that less water is fed to the drum drive whenever the hose tension increases, while a larger water flow is admitted to the vehicle drive. Vice versa, whenever the hose lies slack, and the drum rotating mechanism offers little resistance, then more water enters the actuator, the drum rotates faster and the hose is tightened upon the drum.
The two hydraulic actuators are of the kind having bellows alternately filled and emptied through a reciprocating rotary vane valve, whereby a pivoted lever is urged to and fro. Both actuators are communicatingly connected to the same ports of one common valve which obtains its reciprocating motion through a tension spring attached to the lever of one of the actuators. The valve frequency is controlled by a water meter measuring the water flow passing through the equipment onto the field and an electronic circuit adapted to emit pulses proportional to the revolutions of the water meter, and thus to cause reversal of water flow from one set of bellows to the other. The output of the electronic circuit is adjustable in a manner to permit the vehicle speed to be attuned to the required water quantity distributed over the field, in accordance with the width of the irrigated area, the amount of water per area unit, and other factors.
The beams actuated by the two actuators serve to rotate, in their turn, the hose drum and the driving wheel respectively by pawl-and-ratchet transmissions, in a manner known per se.
Two distribution pipes with equidistant water outlets over its entire length, extend to both sides of the vehicle, perpendicular to the direction of travel, and are supported by two extendible girders which are adapted to be swung into a position close and parallel to the vehicle axis, for the purpose of storing and/or transporting the equipment.
The drum shaft is hollow and is connected at its ends to both branches of the distribution pipe by flexible connectors and shaft seals.